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====== ePDG Monitoring ======

===== Integrated VoWiFi Gateway Monitoring System (ePDG) =====

===== Review of the decision =====

The VAS Experts ePDG Monitoring system provides full operational control of the **fast-epdg** component, the VoWiFi (Voice over WiFi) gateway operating according to 3GPP TS 29.273 and TS 24.302. The gateway provides secure transmission of voice and packet traffic through untrusted Wi-Fi channels with IPSec / IKEv2 tunneling and integration with the EPC core through SWu, SWm, SWx, S2b, S6b interfaces.

The solution provides a single monitoring platform for the mobile operator’s operational services — from the IPSec SA (L3 security) level to the KPI of VoWiFi subscriber experience.

==== Key advantages ====

  * ** Real-time monitoring** — update metrics every 10-15 seconds, directly display the status of IKE SA / Child SA and GTP tunnels in NOC dashboards without delayed aggregation (hereinafter NOC — Network Operation Center, network management center).
  * **Proactive detection of anomalies** — 20+ alarms with automatic escalation in importance. PGW/AAA inaccessibility, increased IKEv2 delays, and an increase in EAP-AKA errors are detected before subscribers notice problems with calls.
  * **Open integration interfaces** — Prometheus, SNMP v2c, Alertmanager webhooks, Grafana support. Integration into the existing NMS/OSS infrastructure without vendor binding.
  * ** Minimum external dependencies at the plugin level** — built-in ''/metrics'' endpoint in fast-epdg, without Java, without JMX, without external agents.
  * **Coverage of the entire SWu → S2b** stack — IKEv2 (SWu), Diameter SWm/SWx/S6b, GTPv2-C (S2b) and GTP-U data plane — all in one place. The 33 metrics cover control plane and data plane.


==== Four-level monitoring architecture ====

^Level ^ Component ^ Technology ^
| **Collection** | Built-in ''/metrics'' endpoint fast-epdg | Prometheus text format over HTTP |
| **Storage** | Prometheus TSDB | Local storage, 15-day storage by default |
| **Visualization** | Grafana + JSON support | Autodownload 4 dashboards |
| **Alerting** | Alertmanager + SNMP Trap Sender | PromQL rules → webhook → SNMP v2c trap |


==== Quantitative review by category ====

^ Category                    ^ Number of metrics  ^ Survey interval  ^ Key indicators                                                                                  ^
| **Config**                  | 2                  | 10 sec           | Configuration status, reload counter                                                            |
| **Network**                 | 1                  | 10 sec           | Node connection status (PGW/AAA/HSS)                                                            |
| **IKEv2 (SWu)**             | 3                  | 10 sec           | Reports by type (IKE_SA_INIT, IKE_AUTH, CREATE_CHILD_SA), delay diagram, errors                 |
| **GTPv2-C (S2b)**           | 4                  | 10 sec           | Messages (Create/Modify/Delete Session), delays, errors, relays                                 |
| **GTP-U data plane**        | 3                  | 10 sec           | Packets/bytes, tunneling errors                                                                 |
| **Diameter (SWm/SWx/S6b)**  | 5                  | 10 sec           | Command code messages (DER/DEA, MAR/MAA, AAR/AAA), delays, errors, watchdog, connection status  |
| **Service KPI**             | 4                  | 10 sec           | Percentage of successful attempts, duration histogram, service availability, uptime             |
| **Session State**           | 4                  | 10 sec           | IKE SA, Child SA, GTP sessions, all users                                                       |
| **Application**             | 3                  | 10 sec           | Number of streams, memory, log messages by levels                                               |
| **System**                  | 4                  | 10 sec           | CPU recycling, memory, memory disposal, open FD                                                 |
| **Total**                   | **33 metrics**     |                  |                                                                                                 |


==== Alarm categories ====

^ Criticism     ^ Alarma                                                                                                                                                                                                                            ^ Description                                                                      ^ Reaction                                                                                         ^
| **Critical**  | ''ePDG_Service_Down'', ''ePDG_High_Attach_Failure_Rate'', ''ePDG_PGW_Unreachable'', ''ePDG_AAA_Unreachable'', ''ePDG_Diameter_Watchdog_Timeout''                                                                                  | Component is unavailable, widespread connection failures, nodes are unavailable  | Immediate escalation: Email + SNMP Trap + Webhook. Repeat every hour                             |
| **Warning**   | ''ePDG_High_IKEv2_Latency'', ''ePDG_High_GTP_Latency'', ''ePDG_High_IKEv2_Error_Rate'', ''ePDG_High_GTP_Error_Rate'', ''ePDG_High_Memory_Usage'', ''ePDG_High_CPU_Usage'', ''ePDG_Low_Disk_Space'', ''ePDG_High_Error_Log_Rate''  | Performance degradation, resource anomalies                                      | Email. Resend every 4 hours. Suppressed if a “Critical” status is present on the same component  |